Cloud system resolving model study of the roles of deep convection for photo-chemistry in the TOGA COARE/CEPEX region
Item
Title (Dublin Core)
Cloud system resolving model study of the roles of deep convection for photo-chemistry in the TOGA COARE/CEPEX region
Description (Dublin Core)
A cloud system resolving model including photo-chemistry (CSRMC) has been developed based on a prototype version of the Weather Research and Forecasting (WRF) model and is used to study influences of deep convection on chemistry in the TOGA COARE/CEPEX region. Lateral boundary conditions for trace gases are prescribed from global chemistry-transport simulations, and the vertical advection of trace gases by large scale dynamics, which is not reproduced in a limited area cloud system resolving model, is taken into account. The influences of deep convective transport and of lightning on NO<sub>x</sub>, O<sub>3</sub>, and HO<sub>x</sub>(=HO<sub>2</sub>+OH), in the vicinity of the deep convective systems are investigated in a 7-day 3-D 248×248 km<sup>2</sup> horizontal domain simulation and several 2-D sensitivity runs with a 500 km horizontal domain. Mid-tropospheric entrainment is more important on average for the upward transport of O<sub>3</sub> in the 3-D run than in the 2-D runs, but at the same time undiluted O<sub>3</sub>-poor air from the marine boundary layer reaches the upper troposphere more frequently in the 3-D run than in the 2-D runs, indicating the presence of undiluted convective cores. In all runs, in situ lightning is found to have only minor impacts on the local O<sub>3</sub> budget. Near zero O<sub>3</sub> volume mixing ratios due to the reaction with lightning-produced NO are only simulated in a 2-D sensitivity run with an extremely high number of NO molecules per flash, which is outside the range of current estimates. The fraction of NO<sub>x</sub> chemically lost within the domain varies between 20 and 24% in the 2-D runs, but is negligible in the 3-D run, in agreement with a lower average NO<sub>x</sub> concentration in the 3-D run despite a greater number of flashes. Stratosphere to troposphere transport of O<sub>3</sub> is simulated to occur episodically in thin filaments in the 2-D runs, but on average net upward transport of O<sub>3</sub> from below ~16 km is simulated in association with mean large scale ascent in the region. Ozone profiles in the TOGA COARE/CEPEX region are suggested to be strongly influenced by the intra-seasonal (Madden-Julian) oscillation.
Creator (Dublin Core)
Salzmann, M.
Lawrence, M. G.
Phillips, V. T. J.
Donner, L. J.
Date (Dublin Core)
2018-01-15
Type (Dublin Core)
Text
Format (Dublin Core)
application/pdf
Identifier (Dublin Core)
10.5194/acp-8-2741-2008
https://acp.copernicus.org/articles/8/2741/2008/
Source (Dublin Core)
eISSN: 1680-7324
Language (Dublin Core)
eng
